Chapter 1 : The Science of Physics

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1-1 . What is Physics?

Physics is Everywhere.

Most do not realize the true impact of physics in our day-to-day lives, however, physics affects us in many ways. Any occurence with temperature, size, motion, position, shape, or color involves physics. The categorization of physics topics can be best illustrated by the chart below:

Areas within Physics

Name: Subjects: Examples:

Mechanics: Motion and its causes: Falling objects, friction, weight, spinning objects

Thermodynamics: Heat and temperature: Melting and freezing processes, engines, refrigeratos

Vibrations and Waves: Specific repetitive motions: Springs, pendulums, sound

Optics: Light: Mirrors, lenses, color, astronomy

Electromagnetism: Electricity, magnetism, and light: Electric charges, circuits, permanent magnets, electromagnets

Relativity: Particles moving at all speeds: Particle collisions, particle accelerators, nuclear energy

Quantum Mechanics: Behavior of submicroscopic entities: The atom and its parts

THE SCIENTIFIC METHOD

Definition: The scientific method is the basis of certian steps common to all good scientific investigations.

Steps of the Scientific Method
1. Make observations and collect data that leads to a question.
2. Formulate and objectively test hypotheses by experiments.
3. Interpret results, and revise the hypothesis if necessary.
4. State conclusions in a form that can be evaluated by others
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*MODELS:
Another important concept to understand about physics is the usage of MODELS. Models are convenient ways for humans to simulate/describe the
physical occurrences of given situations. With models we can more accurately predict and mathematically determine the outcome of physical events.


*HYPOTHESES:
The key to the success of the scientific method is the existence of a controlled experiment. Essentially, this means only one variable can be tested at a time.
And remember, THE BEST PHYSICS HYPOTHESES CAN MAKE PREDICTIONS IN NEW SITUATIONS!!!!


Section Review: Section 1-1:

1.) Name the areas of physics.

2.) Identify the area of physics that is most relevant to each of the following situations. Explain your reasoning.
a. A high school football game
b. Food preparation for the prom
c. Playing in the school band
d. Lighting in a thunderstorm
e. Wearing a pair of sunglasses outside in the sun

3.) What are the steps of the scientific method?

4.) Give two examples of ways that physicists moel the physical world.


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1-2 . Measurements in Experiments

THE SI SYSTEM OF MEASUREMENT

Scientists and Physicists make crucial calculations when they test hypotheses. Therefore, it is equally essential to have a system of numerical order whereupon
numbers, units, measurements, and the handling thereof is consistent. Scientists call this standard system the SI system. (Systemé International).

We may be familiar with derived SI units such as joules or newtons, these units are commonplace, however, they all originate from the basic three standard units of meters, kilograms, and seconds. Units such as newtons, simply stem from those three units in combination, (ex: N=kg x m/s x s).

When dealing within the SI system, it is important to remember that for extreme numbers, big or small, prefixes are used. For example, the speed of light would be expressed as 3.0 x 10 to the seventh

ACCURACY AND PRECISION


Remember, when using the SI system one must consider whether or not measurements are precise, accurate, both or neither.
Precision: describes the limitations of the measuring instruments in use
Accuracy: describes how close a answer is to the actual value or targeted value (determined mathematically)

When using these definitions it becomes necessary to cut off and round numbers in the appropriate form, for this problem scientists developed significant figures.

SIGFIGS

Sigfig Rules:

Rules for determining whether zeros are significant figures:
1. Zeros between other nonzero digits ARE significant
2. Zeros in front of nonzero digits are not significant
3. Zeros that are at the end of a number and also to the right of the decimal are significant
4. Zeros at the end of a number but to the left of a decimal are signigicant if they have been measured or are the first estimated digit; otherwise, they are not significant.

Section Review: Section 1-2:

1.) Which SI units would you use for the following measurements?
a. the length of a swimming pool
b. the mass of the water in the pool
c. the time it takes a swimmer to swim a lap
2.) Express the following measurements as indicated.
a. 6.20 mg in kilograms
b. 3 x10 -9 in milliseconds
c. 88.0 km in meters
3.) Perform these calculations, following the rules for significant figures.
a. 26 x .02584= ?
b. 15.3 / 1.1 = ?
c. 782.45 - 3.5328 = ?
d. 63.528 ÷ 734.2 = ?

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Section 1-3. The Language of Physics


WAYS FOR SCIENTIFIC DATA TO BE COMMUNICATED

When comparing great volumes of information and compilations, it can be a complex and difficult task to sort through information. Therefore, scientists and physicists have turned to utilizing graphs, tables, and equations to make date easier to understand.

Equations are used to process information in a uniform matter so that all people can evaluate data and yield similar results. When units are incorporated into informational exchanges, it is imperative to keep unit transformation uniform. Scientists use what we call DIMENSIONAL ANALYSIS to accomplish just that.

Order of magnitude is used to correspond between the size of amounts and how objective amounts relate to one another correspondingly.

Dimensional analysis is process by which one can convert equal amounts in different units to similar units. For instance, a meter is equal to 100 centimeters. To covert from one unit to another, one takes the amount over 1, multiplied by the unit equivalent of the coverted unit over one, therefore the dimensional analysis would be as follows:

1m/1 × 100cm/1 = 100 cm


100 cm is the final answer.

Section Review: Section 1-3:

1.) Convert 300 kilograms to slugs.

2.) Determine the units of the quantity described by the following combinations of units:
a. kg (m/s) (1/s)
b. (kg/s) (m/s)
c. (kg/s) (m/s)2
d. (kg/s/s) (m/s/ms)
3.) Which of the following is the best order of magnitude estimate in meters of the height of a mountain?
a. 1m b. 10m c. 100m d. 1000m





WORKS CITED:
All information compliments of the textbook.

Holt, Rinehart And.
Holt Physics__. New York: Holt, Rinehart & Winston, 2001.